Glow plug heater control work around ?

[CalG]

I have a SL&H Hurlimann 435 Prince with a Mitsubishi 4 cylinder engine.

The tractor is equipped with an "auto-magic" glow plug timer control. Timing starts when the ignition key is first turned. There is a status display on the console.

However, in cold air (Vermont in winter) the heating timer is woefully inadequate.

A cold start at temps between 10 and 25 F requires activation of the timer at least five times prior to energizing the starter.

Warm weather starts are fine.

I have fitted a block heater to pre-warm the engine. With a half hour plugged in preheat, the engine starts right off with a cycle or two of the glow plug timer.

I'm thinking I would like to do away with the "auto-magic" controller and control the glow plugs via the key switch (it has the "turn counter clockwise: contacts), or fit a "press to energize" button on the dash panel.

Any thoughts on the reversion of modern automation to old school control it your self?

I'm thinking a 40 amp relay to carry the glow current would be enough.

 

[WranglerX]

If the glow plugs are connected to common bus it should be fairly simple to disconnect the wire that energizes them and add a relay and a push button to allow you to manually "heat' the glow plugs... I would be simple to just push the button for 10 seconds or so and crank it up... On my SCUT it has glow plug position on ignition switch but no "magic" or timers, manual simply states hold in "glow plug" position about 8-10 seconds....

30-40 amp relay should be more than sufficient, fortunately they available at almost any local auto parts.... My SCUT only has 5 amp fuse in line with my 3 glow plugs do current draw is not real great, but relay adds reliability factor to take (electrical) load off push button or ign switch.... Size of fuse (yea you should) will be determined on how much combined amperage all four glow plugs draw...

Dale

 

[Dave M7040]

Be careful with re wiring the GP's. Many require some sort of ballast resistor, often called a Glow indicator, to limit the voltage and current the GP's see.

Most technical GP manuals from their manufacturers' warn against applying 12 volts directly to the GP. The danger is that the GP overheats and explodes depositing hard sharp metal and ceramic shards inside the cylinder.

I can only speak for Kubota on this point. The self regulating GP timers are being fooled by the temp signal going from the engine to the controller when a block heater is installed. The warm block makes the controller think the air temp outside is warm. Accordingly, the heating time for the GP's is far less than it should be when the engine, as it cranks, inhales say -30 outside air.

On some Kubota's, the dealer can re program the GP controller to use a different temp sensor other than the block warmed one.

On my Kubota, there is an unpublished way to manually control the GP time. Shuttle in forward. Turn key to start. Nothing happens but the GP's are heating. There is no indicator. Count to 10, shuttle back to neutral and now the engine fires instantly. If you have dealer try talking to the mechanics. Often they have a way to manually control the GP time so they can move machines around the lot during snow removal. The sales people are staying inside so often do not know the little tricks.

Dave M7040

 

[WranglerX]

Would be wise to look up specifications on glow plugs, as mentioned above some may be ok on straight 12 volts some may require dropping resistor (ballast) to prevent premature failure...

Dale

 

[Trillium Farm]

Be careful with re wiring the GP's.The danger is that the GP overheats and explodes depositing hard sharp metal and ceramic shards inside the cylinder.

That's why there is a timer, to protect the engine from bursting GP due to overheating. Even this is not enough for some operators.